HEATS UP WHEN IT'S COLD AND COOL WHEN YOU SWEAT. Only sweat turns the cooling effect of X-BIONIC ®. An intelligent control system with a reliable starter motor: your sweat! Unique, effective and always ready to go into action. Thermal control adjusted: developed by scientists, tested by sportsmen. We all know the unpleasant feeling of being covered in sweat and reunions, the next moment, with goose bumps. The body echoes the warning: risk of cooling. X-BIONIC ® Functional Underwear prevents these cool shots. The sweat is out and the heated air from the body using a unique mode to realize the thermal insulation.